Bancroft is a city in the Gem Valley in Caribou County, Idaho, United States.

According to the United States Census Bureau, the city has a total area of 0.65 square miles (1.68 km2), all of it land.

There were 163 housing units at an average density of 250.8 per square mile (96.8/km2).

21.7% of all households were made up of individuals, and 13.8% had someone living alone who was 65 years of age or older.

There were 172 housing units at an average density of 261.2 per square mile (100.8/km2).

27.1% of all households were made up of individuals, and 18.8% had someone living alone who was 65 years of age or older.